Plastic containers

ABSTRACT

A PLASTIC CONTAINER THE INSIDE OF WHICH HAS AN AREA OF ROUGHNESS SO THAT WHEN THE CONTAINER IS FILLED WITH YOGURT OR OTHER SIMILARLY VICOUS PRODUCT, THE TENDENCY OF THE PRODUCT TO SEPARATE INTO INTO ITS COMPONENTS OR MORE INDEPENDENTLY OF THE CONTAINER WALL IS LESSENED.   D R A W I N G

July 4, 1972 A. A. ANDROS 3,674,512

PLASTIC CONTAINERS Filed Nov. 21, 1969 2 Sheets-Sheet l FIG. 1 D /6 x /0 M I/ 2% FIG. 2

22 H 11 I 1 5Q INVENTOR. ARTHUR A4 ANDROS WMQ M- Attorney:

July 4, 1972 A. A. ANDROS 3,674,532

PLASTIC CONTAINERS Filed Nov. 21, 1969 2 Sheets-Sheet 2 FIG. 3

INVENTOR. ARTHUR A. ANDROS United States Patent US. Cl. 99-178 Claims ABSTRACT OF THE DISCLOSURE A plastic container the inside of which has an area of roughness so that when the container is filled with yogurt or other similarly viscous product, the tendency of the product to separate into its components or more independently of the container wall is lessened.

BACKGROUND OF THE INVENTION (1) Field of the invention This invention relates to plastic containers suitable for packaging semi-fluid and viscous foodstuffs.

(2) Description of the prior art Plastic containers have many advantages for packaging foodstuffs, and are widely used. The containers, if properly designed, are easily made in large quantities, are capable of being filled in automatic machinery, and are low enough in price to be thrown away after use. Moreover, they can be sealed efiiciently with automatic machinery by applying a cover to the open top.

Yogurt and similar dairy-based products in particular have been packaged in tub-shaped plastic containers having a relatively wide top covered with a plastic or foil lid. In practice, however, it has sometimes been found that in the transport of yogurt packages, suflicient motion is imparted to the contents to cause some separation of the components into a fatty phase and an aqueous phase. This is a disadvantage and tends to affect the appearance, taste and fiow of the comestible.

SUMMARY OF THE INVENTION There has now been developed a container which overcomes the difficulty described above.

Accordingly, the main object of the present invention is to provide a plastic container which will reduce the tendency of yogurt or other similarly viscous material packaged in the container from separation into its components during transport.

Another object of this invention is to provide method and means for providing a plastic container having an area of internal roughness.

Other objects and advantages of the present invention will in part be obvious and will in part appear hereinafter.

These and other objects are attained in a plastic container which has over a sufficient area a degree of roughness such that when the container if filled with yogurt or similarly viscous product the tendency for it to move independently of the container is lessened.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view, in section, illustrating a container of the present invention which has an area of the internal wall roughened;

FIG. 2 is a side view, in section, illustrating an alternative embodiment of the container of the present invention having a restricted ring at the upper portion thereof, and

FIG. 3 is a side view, in section, illustrating another alternative embodiment of the container of the present in- "ice vention wherein the roughened area is in the form of a band of the upper portion of the inside. wall of the container.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring in detail to the figures and drawings and more specifically FIG. 1, there is schematically shown a container 10 composed of a plastic material having an internal area 12 of the container wall 14 roughened to a greater degree than the remaining portion of the inside wall 14. In this embodiment, the roughened internal area 12 is located towards the lower part of the container and the wall is inclined from the vertical at an angle equal to a to present a frustoconical shape with the wider end 16 being uppermost.

FIG. 2 shows a modified form of the container of FIG. 1 illustrating a container 20 having a restricting ring 22 to hold and support a cover near the upper portion 24 of the container 20 as well as having an area of roughness 26 towards the lower part of the inside wall of the container.

FIG. 3 illustrates an alternative embodiment of container 30 showing the roughened band 32 at the upper portion of the container 30. Also included are two extremely narrow external bands 34 and 36 used in the injection forming of the container to retain the container on the plunger of the forming equipment during discharge. Also shown in this particular embodiment are insteps 38 at the lower internal portion of the container for stacking purposes. This particular container has been found very suitable for the packaging of yogurt. In addition, the rim 40 is especially suitable for the heat sealing of biaxially oriented film across the top to obtain a hermetic seal which provides both an air tight package and a cup-like container for ready consumption of the contents when open.

In summary, the plastic container of the present invention is one in which the inside wall surface has a sufficient area with a degree of roughness such that when the container is filled with yogurt or similar product the tendency of the product to move along the wall independently is lessened.

Although the container can be of various shapes; for example, cylindrical, frustoconical and the like, the frustoconical shape having the wider end as the open end is preferred. In the preferred frustoconical embodiment, the walls are preferably inclined from the vertical at an angle a which should not be more than about 10 degrees nor less than 2 degrees with the ratio of the diameter of the open top to the vertical height of the container being most preferably between 3:1 and 1:3, and more preferably between 2:1 and 1:3. Excellent results are obtained when the latter is closer to 1:3.

The roughness can be present either on substantially all of the inside surface of the container, or on a part only, preferably in the form of a band which may be located on the lower or upper section of the inside wall with a band width being preferably between to inch wide. In some instances it is more desirable to locate the band circumferentially extending around the upper portion of the inside wall of the container such that the level of the viscous products prior to consumption will lie within the band area. The roughness can be imparted by a suitable application of mechanical forces to the inside of the molded container; for example, by treatment with an abrasive means. Preferably, however, the required roughness is obtained during the process of molding the container. In order to do this the portion of the metal mold which shapes the inside of the container can be suitably roughened on its surface, for instance by shot or sand blasting; the mold container will then contain a reproduction of this roughening. Other methods of roughening the mold include acid etching and erosion by electric discharge. The technique of toughening the surface of the appropriate member of the mold can very usefully be employed in a process in which injection molding is employed to make the containers. The optimum surface roughness can be described as being between 40 to 300 microinches measured in accordance with the General Electric Surface Roughness Scale which is available to the public and described in General Electrics publication GEL-1136.

In practice, the advantages obtained by the above described roughness in the container can be augmented by a number of other factors. For example, restrictions of various kinds can be molded into the inner surface of the container. For example, if the name or trademark of the ultimate user is embossed or indented (during molding) on the outer face of the container the effect will be to cause constrictions in the inner face, that is to say convex dispositions of the surface of the container when viewed from inside the container. These will co-operate with the above described roughness in resisting the tendency of the contents such as yogurt to move relative to the container tending to cause separation of the components. Similar beneficial effects may be obtained by ensuring that the container has a neck" or ring (or possibly some pattern of embossed decoration) at some point, usually towards the top of the container. Again this will be an area where at certain points the inner faces of the container will be closer to each other than at adjoining portions.

The container of this invention is particularly valuable when used in conjunction with natural yogurt, that is to say one in which the curd is formed within the container ready for sale. More specifically, where milk and the appropriate bacteria are placed in containers which are then heated at 3050 C. for 2 to 5 hours until the curd has been formed.

The containers can vary in capacity but are most often within the 200-300 cc. or A pint range, although they can be smaller for example, 150 cc. or lower capacity. Other products which can be packed in them with advantage are typical dairy products such as creams, certain cheeses, rigid milk puddings, and jellies.

A typical plastic container to which the invention is usefully applied is made from transparent polystyrene by injection molding, and has a wall thickness of about 0.3 to 1.0 mm. and a capacity of about 200 to 300 cc. It is frustoconical in shape with the wider end uppermost, and can be closed with an aluminum foil lid.

The plastic material from which the container is produced is a thermoplastic resin derived from a monomer containing an ethylenic linkage. It can be instance be made from polyethylene, polypropylene, polyvinyl chloride, or

a polyalkenyl aromatic material such as for example a styrene. Polystyrene itself is eminently suitable and this enables a transparent container to be utilized. An impact polystyrene, that is, a polystyrene the impact properties of which have been improved by the incorporation of a minor proportion of a rubber (normally a synthetic rubber), can also be employed, and its use enables containers having a thinner wall thickness to be used.

The container can be molded in any convenient way, but is usually made by injection molding the resin. Thermoforming of sheet using a plug can also 'be employed, or the containers can be blow molded.

What is claimed is:

1. As an article of manufacture, a dairy product enclosed within a container having a roughened annular band on its inner surface spaced below the opening of said container in contact with said dairy product, said band being characterized as having a roughness value of between 30 to 400 microinches, the remainder of the inner surface of the container being smooth relative to said band, whereby the tendency of said dairy product to move along the inner surface independent of the container is lessened.

2. The article of claim 1 wherein said dairy product is yogurt.

3. The article of claim 1 wherein the capacity of said container is between 200 to 300 cc., the width of said band is between to 4 inch, and the upper level of the dairy product lies within said band.

4. The plastic container according to claim 1 wherein the container is made by injection molding the thermoplastic resin.

5. The plastic container according to claim 1 wherein the roughness in the container is augmented by a circumferentially spaced stacking insteps restriction molded into the inner surface of the container.

References Cited UNITED STATES PATENTS 2,731,093 l/l956 Gordon ISO-0.5 X 3,434,5 88 3/ 1969 Kirkpatrick 220-83 X 3,061,139 10/ 1962 Edwards 220-44 R 3,173,571 3/1965 Cserny 220-44 R FOREIGN PATENTS 463,377 9/1968 Switzerland use 220-72 GEORGE E. LOWRANCE, Primary Examiner US. Cl. X.R.

99-171 TC; 220-83; 229-15 B 

